An iron-boron-silicon amorphous alloy containing, for example, 3 wt. % boron and 5 wt. % silicon has a high magnetic permeability and is widely applied as a magnetic material. Such an iron-boron-silicon amorphous alloy is obtained by supplying a molten iron-boron-silicon alloy containing 3 wt. % boron and 5 wt. % silicon onto the surface, for example, of a cooling rotary drum rotating at a prescribed circumferential speed, and rapidly cooling the molten alloy to solidify same into a thin sheet shape.
The above-mentioned iron-boron-silicon alloy is conventionally manufactured as follows: Into an electric furnace are charged, at prescribed ratios, a boron raw material comprising at least one of a boron ore such as a sodium borate ore a calcium borate ore or a colemanite ore, and a boric acid obtained by treating the above-mentioned boron ore by an acid, an iron-bearing source such as an iron ore or a scrap, and a carbonaceous reducing agent such as coke or coal. This charge is melted and refined in the electric furnace, and then solidified to prepare a solid iron-boron alloy, i.e., a ferroboron. Then, the thus prepared solid ferroboron and at least one of separately prepared solid silicon and ferrosilicon are added at prescribed ratios to a molten iron having a carbon content of up to 0.2 wt. % received in a melting furnace, and the mixture is melted, thereby manufacturing an iron-boron-silicon alloy.
The above-mentioned conventional method for manufacturing an iron-boron-silicon alloy has the following problem: The conventional manufacturing method comprises the preparing step of ferroboron in the electric furnace and the melting step of ferroboron and silicon into the molten iron in the melting furnace. The conventional manufacturing method is therefore complicated and requires much electric energy, resulting in an increased manufacturing cost of the iron-boron-silicon alloy.
Under such circumstances, there is a strong demand for the development of a method for economically manufacturing an iron-boron-silicon alloy through simple steps without requiring much electric energy, but such a method has not as yet been proposed.